Recognising Tissues in the Gas Exchange System
Cartilage
- The cartilage in the trachea has a ‘glassy’ appearance due to its translucent protoplasm
- It contains no nerves or blood vessels
Cartilage micrograph diagram
Cartilage micrograph, similar to that found in the gas exchange system
Cartilage SEM diagram
Electron micrograph of cartilage tissue
Ciliated epithelium
- Ciliated epithelial cells are distinctive due to their narrow cell bodies and hair-like cilia located along the apical layer
- The cilia are tiny projections which greatly increase the surface area of the cell
Ciliated epithelium photomicrograph diagram
Photomicrograph of a ciliated epithelium tissue in the gas exchange system
Ciliated epithelium electron micrograph diagram
Electron micrograph of a ciliated epithelium tissue in the gas exchange system
Goblet cells
- Goblet cells can be found scattered among the ciliated epithelium of the trachea and bronchi
- They are distinctive in the epithelium due to their lack of cilia (although they still have some microvilli projecting outwards)
- The nucleus is found towards the basal (bottom) layer of the cell, with a large Golgi apparatus and mucus granules found towards the apical layer
Light micrograph of some goblet cells diagram
Light micrograph showing goblet cells as they would be found in the gas exchange system
Electron micrograph of some goblet cells diagram
Electron micrograph showing goblet cells as they would be found in the gas exchange system
Squamous epithelium
- Squamous epithelium is made of thin, flat squamous cells
Light micrograph of the squamous epithelium diagram
Light micrograph showing the squamous epithelium as it would be found in the gas exchange system
Electron micrograph of the squamous epithelium diagram
Electron micrograph showing the squamous epithelium as it would be found in the gas exchange system
Smooth muscle
- The cells of smooth muscle are tightly packed and are found beneath the ciliated epithelium
- Unlike skeletal muscles, they are not striated and so don’t show any cross stripes under a microscope
Light micrograph of the smooth muscle diagram
Light micrograph showing the smooth muscle as it would be found in the gas exchange system
Electron micrograph of the smooth muscle diagram
Electron micrograph showing the smooth muscle as it would be found in the gas exchange system
Capillaries
- Capillaries are distinctive from other blood cells due to their tiny diameter (~4 μm)
- Their walls consist of a single layer of epithelial cells
Light micrograph of capillary tissue diagram
Light micrograph showing the capillaries as they would be found in the gas exchange system
Electron micrograph of the capillaries diagram
Electron micrograph showing the capillary tissue as it would be found in the gas exchange system
